I. Field
The present disclosure relates generally to electronics, and more specifically to an amplifier.
II. Background
Amplifiers are commonly used in various electronics devices to provide signal amplification. Different types of amplifiers are available for different uses. For example, a wireless communication device such as a cellular phone may include a transmitter and a receiver for bi-directional communication. The transmitter may utilize a driver amplifier (DA) and a power amplifier (PA), the receiver may utilize a low noise amplifier (LNA), and the transmitter and receiver may utilize variable gain amplifiers (VGAs). Amplifiers may also be used for active filters and other circuit blocks within the transmitter and receiver.
Various classes of amplifiers may be used for signal amplification. A class A amplifier operates in a linear region all the time and may have better linearity at the expense of greater power consumption. A class B amplifier typically employs two complementary output transistors, with each output transistor being turned on for half of the time and turned off for the other half of the time. A class B amplifier has lower power consumption than a class A amplifier but may be susceptible to crossover distortion due to the turn-on of one output transistor not matching the turn-off of the other output transistor. A class AB amplifier also employs two complementary output transistors (similar to a class B amplifier), albeit with each output transistor being turned on for more than half of the time in order to reduce crossover distortion. A class AB amplifier may provide good compromise between linearity and power consumption.